# Find hte sum of series

## Homework Statement

heres the equation: http://img255.imageshack.us/img255/1669/untitledfa5.jpg [Broken]

## Homework Equations

i think we use cos(x)

## The Attempt at a Solution

i know that cos(x) = cos(pi)

so the limit is -1?

whats the sum, i'm a bit confused.
must be in simplest form
what must i show. help.

Last edited by a moderator:

Dick
Homework Helper
I don't think you can express the sum much more simply than -1. The 'limit' you are talking about is the 'sum', right?

arildno
What you must show is that the infinite series representation of $\cos(\pi)$ is identical to the infinite series given in the exercise.